This invention relates to a novel polymeric pulley for driving the cooling fan of an internal combustion engine, and to the combination of the polymeric pulley with a housed bearing assembly.
In recent years, fans for internal combustion engines have been considerably improved and lightened in weight, being formed of special polymeric structures weighing only a fraction of prior cooling fans. As such, rotation of the fans can be quickly initiated, stopped and regulated for optimum cooling and power usage. However, the pulley and hub drive mechanism for such fans has continued to be of heavy structure, typically of cast iron weighing well over seven pounds. This pulley and hub drive is normally, although not always, connected to a thermostatically controlled clutch for the fan. A lower mass pulley would help reduce belt wear, due to its lower moment of inertia, during speed changes. It would also permit faster engine acceleration. Reduction in mass would also add to the load carrying capacity of the vehicle.
Moreover, the typical structure is expensive to manufacture. The cast iron pulley and integral bearing housing are largely specially made for the particular model engine accommodated, involving costly casting and machining operations and requiring large inventory management. Each pulley requires a number of different machining operations and balancing. It would be advantageous to substitute this heavy construction with a lightweight assembly requiring little or no machining or balancing. Conceivably, use of polymeric materials in place of cast iron would help to secure these advantages.
Plastic or polymeric pulleys have been known heretofore. Many of these are for low duty usage, being simply solid polymeric members or, if intended for somewhat heavier duty, are composite assemblies with special metal components incorporated. Polymer and metal containing pulleys of various types are set forth in U.S. Pat. Nos. 2,760,378, 3,367,199, 3,651,705, 3,696,685, 3,772,928, 3,788,155, 4,034,616, 4,177,685, 4,326,849, 4,364,736, 4,366,609, 4,468,210, 4,473,363, 4,548,592, 4,571,226 and 4,652,474.